The aims of this revised application are to multidimensionally evaluate the sequelae of psychological trauma in preschool-age children. The proposed plan is part of my programmatic series of studies on the developmental, neurobiological, and psychopathological impact of trauma on young children. I propose to recruit two samples of 70 children each, age 3 through 6 years, who have experienced two different kinds of traumatic events: single-blow acute trauma and repeated/witnessed trauma from domestic violence. We will recruit until we have 35 children with posttraumatic stress disorder (PTSD) and 35 children with subthreshold symptoms of PTSD in each group. There will also be a group of 70 healthy control children. The aims and hypotheses are: (1) The primary caregiver of children with PTSD will show more negative emotional regulation of their children compared to the caregivers of traumatized children without PTSD and to the parents of healthy control children. This effect will be shown two ways: (a) the parents of PTSD children will show more negative sequential interactions with their children in our laboratory and (b) the parents of PTSD children will score higher on self-report of avoidant coping behavior in the home; (2) Children with PTSD who score higher on measures of dissociation will slow down their heart rate in response to trauma stimuli. We will attempt to replicate this association that has previously been demonstrated in adolescents and adults, and is one piece of an emerging dissociative subtype of trauma response. The anticipated differences will also be analyzed separately within each trauma group to determine if there are differential impacts from single-blow and repeated/witnessed types of trauma at this early age. We have developed a model of how parent factors impact on child factors through the mechanism of parent-child relationship factors, which ultimately impact on the development of symptoms of PTSD. This revised application focuses more on how the mechanism of the parent-child relationship may explain the development of psychopathology in early childhood. Ancillary explorations that are important to investigating this model will include how parental symptoms, parent dissociation, parent heart rate reactivity, and child comorbid symptomatology correlate with each other and with the parent-child relationship. [unreadable] [unreadable]